The purpose of this work is to trace the evolutionary history of matrotrophy in plants, and to explore matrotrophy as a major cladogenic mechanism. Molecular sequence information has been used to design an oligopeptide representing a conserved 10 amino acid extracytoplasmic loop in an evolutionarily conserved family of cell membrane hexose transporters. The oligopeptide and corresponding polyclonal antibody are obtained from a commercial source and used in comparative tissue-level and taxon-specific studies of transporter expression of specific plasma lemma hexose transporter proteins which occur at the plant placenta (the morphologically-specialized apoplastic junction between sporophytic and gamtophytic tissues.) Preservation of antigenicity is expected to be enhanced by the use of high pressure freezing.